1. Field of the Invention
This invention relates generally to wireless communication. More particularly it relates to route guidance (navigation) on a mobile wireless device including global positioning satellite (GPS) capability.
2. Background of Related Art
Navigation devices are typically GPS-based electronic systems used in a vehicle to provide a real-time map of the vehicle's current location, together with step-by-step directions to a requested destination.
All navigation devices must handle the condition in which the user deviates (leaves) their intended route. When this condition occurs, the application typically determines the user's current location by “reverse geocoding” the last GPS fix from the device. This new current location is then used to generate a new route to the original destination.
Reverse geocoding is a process of returning an estimated position on a street as it relates to a given latitude/longitude coordinate. Mobile applications available today use a simple reverse geocoding algorithm to locate the closest point on any road segment near the GPS coordinate received from the device.
However, due to the inherent inaccuracy of a GPS fix, this simplistic approach may locate the user on an incorrect road that is near the user's true location. Since this occurs while the user is driving and after they have deviated from the intended route, the cost of an incorrect reverse geocode is quite high since the new route will also be incorrect.